Dispenser apparatus

ABSTRACT

A dispenser apparatus comprises a housing that includes a chamber for holding a sample. A member in the housing is moved relative to the chamber from a first position to a second position to aspirate material into the chamber and is moved from the second position to the first position to dispense material from the chamber. Pressure in the chamber is increased at the end of the dispensing movement to discharge all of the material from the chamber.

[4 1 May 29, 1973 United States Patent 1 Zindler XX AA 33 22 44 l/ 33[54] DISPENSER APPARATUS 3,546,946 12/1970 Smith 3,622,047 11/1971Oberli................. [75] Inventor. Jerrold Zindler, Cambridge, Mass.3,656,473 W972 Sodickson et al......

[73 Assignee:

Instrumentation Laboratory, llnc., L i t M Primary Examiner-Lloyd L.King July '22, 1971 Appl. No.: 164,995

Assistant ExaminerMichael Mar Attorney-Willis M. Ertman [22] Filed:

[57] ABSTRACT A dispenser apparatus comprises a housing that in- [52]1.1.8. CL.................222/363, 73/423 A, 73/425.6

cludes a chamber for holding a sample. A member in [51] Int. 10/00.222/309, 361-363,

the housing is moved relative to the chamber from a [58] Field ofSearch.....................

first position to a second position to aspirate material into thechamber and is moved from the second position to the first position todispense material from the chamber. Pressure in the chamber is increasedat the end of the dispensing movement to discharge all of the [56]Reierences Cited UNITED STATES PATENTS material from the chamber.

3,607,094 9/l97l Beer 6 X 3,550,453 12/1970 Lightner et al.................73/423 A X 9 Claims, 8 Drawing Figures ill ll lDISPENSER APPARATUS SUMMARY OF INVENTION This invention relates todispenser systems and more particularly for systems particularly adaptedfor dispensing minute quantities of materials in accurate amounts.

It is frequently necessary to provide a precise amount of a known orunknown material for use in connection with a chemical analysis. Inphotometric analyses, for example, measurements may be made directly, bycomparison with a standard, or as a function of the rate of chemicalchange. Such techniques are frequently employed in the analysis ofprecious fluids such as blood or other body fluids. For example, achemical analysis of a sample of such a fluid for enzymes, hemoglobin,chloresterol, glucose, etc., provides useful diagnostic information;While laboratory services performing such analyses are available, theuse of such services often entails the delay of several days or morebefore analysis information is available. Accordingly a need exists inthis field for instrumentation that provides accurate chemical analysisdata and that can be operated by untrained personnel. Suchinstrumentation would assist laboratories in contending with theshortage of skilled personnel. As an adjunct to the performance of suchanalyses, however, it is necessary to provide a system for measuring outquantities of particular materials to be employed in the chemicalanalysis in precise amounts, and it is an object of this invention toprovide novel and improved apparatus for this purpose.

Another object of the invention is to provide novel and improvedapparatus and systems for the accurate dispensing of different andminute amounts of materials.

Another object of the invention is to provide novel and improveddispensing systems which are easy to operate and which a variety ofdifferent amounts may be easily selected by an untrained operator.

In accordance with the invention there is provided dispenser apparatuscomprising a housing that includes a chamber for holding a sample, thechamber having a port through which the sample material is dispensed. Amember, coupled to the housing, is movable relative to the chamber froma first position to a second position to aspirate material into thechamber through the port andon further movement, to dispense materialfrom the chamber through the port. The apparatus further includes meansto increase the pressure in the chamber to supplement the dispensingaction produced by the further movement of the member.

In particular embodiments, the housing has a bore, the movable member ismounted in the bore for reciprocating movement, and rack and piniongearing is employed to reciprocate the member. The pressure increasingmeans in such embodiments includes a blower, a passage between theblower and the chamber and valve means responsive to movement of thememher to control the flow through the passage. In a preferredembodiment, the valve means comprises a seal member mounted in thehousing and a cooperating bypass portion on the member so that movementof the member to a predetermined position positions the bypass portionin bridging relation to the seal member so that the passage between theblower and the chamber is open. Also, the chamber, in preferredembodiments, is defined by a replaceable member that is conical inconfiguration, the port being formed at the conical tip of the memberand the member being releasably secured to the housing at its endopposite the port.

A preferred embodiment of the invention is employed in photometricanalysis instrumentation for performing chemical analyses on preciousfluids such as blood to provide medically useful diagnostic information,and is designed to dispense material in quantities of 25, 50, 100, or200 microliters to an accuracy of i1 percent under the control of a cardreader, with a card containing data correlated with material to bedispensed into a container for use in a photometric analysis of theresulting mixture of materials.

Other objects, features and advantages of the invention will be seen asthe following description of a particular embodiment progresses, inconjunction with the drawings, in which:

FIG. 1 is a perspective view of components of a biochemical analysissystem incorporating apparatus constructed in accordance with theinvention;

FIG. 2 is a perspective view, with components removed, of dispensingapparatus employed in the system shown in FIG. 1;

FIG. 3 is a top view, with parts broken away, of the dispensingapparatus shown in FIG. 2;

FIG. 4 is a front elevational view of the dispensing apparatus shown inFIG. 3;

FIG. 5 is a sectional view of the dispensing apparatus taken along theline 55 of FIG. 4;

FIG. 6 is an enlarged view of a portion of the dispensing apparatusshowing details of the valve means included therein;

FIG. 7 is an enlarged view of flag structure employed in the dispensingapparatus; and

FIG. 8 is a block diagram of logic circuitry employed in the dispensingsystem.

DESCRIPTION OF PARTICULAR EMBODIMENT With reference to FIG. 1, there isshown a biochemical analysis instrument that includes a housing 10 onwhich is mounted a dispenser unit 12 that has two dispensing sections14-1 and 14-2 and corresponding dispenser control switches 16-1 and16-2. To the right of the dispenser unit 12 is an incubator section 18and above section 18 is a card receiving slot of card reader unit 20.Above and to the rear of the card reader unit 20 is a photo-metersection that includes a port 22 for receiving a cuvette assembly 24 anda digital photometer output display 26. Used with this instrument is thecuvette assembly 24 and a card 30 that includes a data section 32,having-photometer calibrating and control information and dispensercontrol information correlated with material in that cuvette assembly,and an instruction section 34.

The cuvette assembly 24 includes three sample chambers 36-1, 36-2 and36-3 of five milliliters volume each. Each chamber has two spaced sidewalls with parallel optical windows therein and is constructed of highquality optical material, the material employed in a preferredembodiment being a transparent TPX methyl pentane polyolefin plastic. Aport 38 in the upper wall of each chamber is sealed by a frangiblesection which may be broken away to permit introduction of material intothe corresponding sample chamber 36.

Additional details of the dispenser may be seen with reference to FIG. 2which shows components of the dispenser as exposed when the cover isremoved. The dispenser includes a support plate on which is disposed asupport body 42. Depending from body 42 are tubular housing members44-1, 44-2 each of which has a replaceable conical chamber member 46secured at its lower end. Disposed for reciprocating movement withineach member 44 is a shaft 48 which at its upper end has formed on it arack gear portion 50 that is engaged by pinion gear 52. Gear 52 is inturn mounted on a shaft 54 driven by reversible motor 56. Secured at thetop of each shaft 48 is a laterally extending arm 58 which carries adepending flag or index member 60. That indexmember is disposed in aslot defined between a front member 62 that houses two light sources anda rear member 64 that houses three light sensors. Signals produced bythe sensors as a function of movement of the flag or index member areemployed to control the operation of the dispenser apparatus.

Additional details of the dispenser apparatus may be seen with referenceto FIGS. 3-7. As shown in those figures, the apparatus includes supportplate 40 and a printed circuit board which carries circuit componentsfor the control of the dispenser apparatus. Board 70 is clamped tosupport plate 40 by suitable fastenings including nut 72 which engageshousing 74 of motor shaft 54. Pinion gear 52 is mounted on shaft 54 andengages rack gear 50. As best seen with reference to FIG. 5, movableshaft member 48 is a cylinder, one-eighth inch in diameter in thisembodiment. A toroidal groove 78, 0.020 inch in maximum depth and 0.125inch in length is formed in cylindrical portion 76 adjacent tip 80.

The cylindrical portion 76 is mounted within housing assembly 44 whichincludes an outer member 82 having an end portion 84 of reduced diameterwith a groove 86 in it in which an O-ring 88 is secured. A bore 90 isformed in the lower portion of member 82 and a second bore 92 of largerdiameter is formed in the upper portion, the transition between the twobores being defined by shoulder 94. Member 82 has an enlarged headportion 96 in the outer surface of which is formed annular groove 98 inwhich is disposed a sealing O-ring 100 and annular manifold groove 102which has a radial passage 104 communicating therewith.

Insert member is disposed within bore 92 and includes an internal groove112 at its lower end in which a seal member 114 is disposed, an annularrecess 116 in its outer surface that extends its length, an internalgroove 118 at its upper end which receives seal ring 120, an annularmanifold groove 122 and a radial passage 124 that communicates withgroove 122. The inner bore 126 of member 110 is of the same diameter asbore 90. A retaining plate 130 is seated in shoulder 132 formed in theinterior of support member 42 and the assembly of members 82 and 110 isin turn seated on plate 130 and secured to support member 42 by clampplate 134 and bolts 136. Support member 42 has a port 128 in its rearwall in which conduit 138 is thrcadedly received. At the upper end ofmember 42 is a port 140 in which a bushing 142 is disposed to provide aguide for the upper end of member 48.

Additional details of the valve structure that is formed by seal member114 and recess 78 may be seen with reference to FIG. 6. Seal member 114includes an annular resilient core member and a split toroidal collarmember 152 of polytetrafluoroethylene which provides a resilient, lowfriction seal surface against the cylindrical wall surface of shaft 76.In the position shown in FIG. 6, the valve members function to close thepassageway formed by bore 126 of member 110 from bore 90 of outer member82. When the shaft 76 is moved downwardly to the position shown in FIG.5, the valve is opened. In this position, air under pressure supplied bya blower connected to conduit 138 is applied through manifold groove102, radial passage 104, manifold groove 120 and passage 122 to bore 120for flow down past recess 78 through bore 90 to the conical chamber 46secured by O-ring 88 on the lower end of member 82 to increase thepressure in that chamber to supplement the action of plunger 76 indischarging material through the port at the tip of the conical chamber46.

The arm member 58 that is secured at the upper end of plunger member 48(as best seen in FIG. 3) includes a head portion 188 that is disposedover the end of member 48 and is secured with set screw 160. Itslaterally extending arm portion 162 has index member 60 secured to it bybolt 164. Additional details of index member 60 may be seen withreference to FIG. 7. Each index member includes a glass substrate thatis 2.27 inches in length and 0.75 inch in width. An opaque flag marking172 is formed on substrate 174. The lefthand section of flag marking 172includes a lower travel limit reference 174 and an upper travel limitreference 176. The righthand section of the flag marking 172 includes adatum or reference mark 178 and four parallel signal marks 180-1 180-4.Mark 180-1 is spaced 0.137 inch from datum mark 178; mark 180-2 isspaced 0.265 inch; mark 180-3 is spaced 0.521 inch; and mark 180-4 isspaced 1.032 inch from the datum mark 178 corresponding to 25,50, 100,and 200 microliters, respectively.

Each index member 60 extends downwardly from support arm 162 and passesthrough the guide passage 182 between light source housing member 62 andsensor housing member 64. As will be seen with reference to FIG. 3,light source 184-1 is aligned with sensor 186-1 and arranged so that thelefthand section of the flag marking 172 is interposed between thatsource 184-1 and sensor 186-1. The second source 184-2 is aligned withthe right vertical edge of the flag marking so that the righthandportion of the flag marking is interposed between source 184-2 andsensor 186-2 while sensor 186-3 is disposed for uninterrupted viewing ofsource 184-2 and functions as a reference sensor. A lamp 188 mounted onsupport 70 is visible through aperture 190 (FIG. 1) in the cover housingof the dispenser apparatus.

A better understanding of the operation of the dispenser system may behad with reference to FIG. 8. That control logic responds to theoperation of switch 16, the operation of which controls three flipflops, a flag flip flop 200, a direction control flip flop 202 and amotor power control flip flop 204. Switch 16 is a two position switchwhich, when moved to engage upper contact 206, generates an aspiratesignal (providing that the system is not in aspirate mode as indicatedby a conditioning signal on line 207 of AND circuit 208) that clears theflag flip flop 202, sets the motor direction flip flop 202 and sets themotor power flip flop 204 (this setting of flip flops 200, 202 and 204establishes the aspirate mode). When switch 16 is moved to engage lowercontact 210, a dispense signal clears flip flops 200 and 202 and setsflip flop 204 establishing system dispense mode. The outputs of flipflops 202 and 204 control the energization of dispense winding 212 ofmotor 56 and aspirate winding 214 of that motor. Blower motor 216 isenergized in response to the output of one shot circuit 218 (through ORcircuit 217 which has a second input over line 219 from the otherdispenser) which in turnis triggered by a lower travel limit signal fromlogic 220 which responds to signals from photocell 186-1, applied overline 222. The logic also includes a counter 224 which is stepped bysignals from sensing photocells 186-2 and 186-3 over line 226 when thesystem is in aspirate mode as indicated by conditioned AND circuit 228;and a compare circuit 230 which compares the output of counter 224 withsignals from card reader over line 232. The output of compare circuit230 over line 234 clears flip flop 204 via OR circuit 236.

Placing switch 16 in the aspirate position completes a circuit tocontact 206 and through OR circuit 240 clears flip flop 200 through ORcircuit 242 sets flip flop 202 and through OR circuit 244 sets flip flop204. The resulting three outputs cause AND circuit 246 to produce anoutput that is applied to one shot 248 and that circuit in turn producesan output of 100 milliseconds duration over line 250 to reset counter224. The set flip flop 202 also applies conditioning level to ANDcircuit 228 and through'in'verter 252 removes a conditioning level fromAND circuit 208. The output of flip flop 204 conditions AND circuit 254and as one shot 218 is not producing an output, inverter 256 provides asecond conditioning to AND circuit 254 and the resulting output causesAND circuit 260 (conditioned by the output of inverter 258) to energizethe aspirate winding 214 of motor 56. The setting of motor flip flop 204also energizes lamp 188. The energization winding 214 of motor 56 startsraising shaft 48 from the datum reference point (indicated by the edge178 disposed between source 184-2 and sensor 186-2), and this upwardmovement of shaft 48 draws material from a supply through the port atthe end of the sample tip 46 into the sample chamber 46. The indexmember 60 moves with the aspirating member 48 and that movement issensed by the light source-photocell combination. Each transition fromlight to dark produces a pulse on line 226 which is passed by ANDcircuit 228 to step counter 224. Digital signals fromcard reader 20 areapplied over lines 232 to compare circuit 230 and when the setting ofcounter 224 is the same as the card reader digital signals on lines 232,the compare circuit 230 produces an output over line'234 to clear flipflop 204 and de-energize winding 214 and lamp 188. Thus, drive motor 56is stopped and a precise amount of material as determined by the signalsfrom card reader 20 is stored in the chamber defined by the sample tip46.

The supply of material is then removed from beneath tip 46, and afterits frangible port 38 has been opened, the appropriate chamber 36 of thecuvette 24 to be filled is placed under the dispenser. The controlswitch 16 is then moved to dispense position completing electricalcircuit to contact 210 which is passed through OR circuit 240 to clearflip flop 200 through OR circuit 262 to clear flip flop 202 and throughOR circuit 244 to set flip flop 204. The resulting output signals areapplied to condition AND circuit 264 and its output in turn energizesdispense winding 212 so that motor 56 drives shaft 48 in the dispensedirection. Signals on line 226 are blocked from application to counter224 by the removal of conditioning signal from AND circuit 228 upon theclearing of flip flop 202.

When the lower travel limit (edge 174) is reached, the signals fromsensor 186-1. on line 222 and from sensors 186-2 and 186-3 on line 226causes logic 220 to generate an output on line 270 which sets flip flops200, 202 and 204. The signal on line 270 also triggers one shot 218 togenerate an output of two seconds duration to energize blower motor 216and apply air pressure to conduit 138. At this time, shaft 48 is in theposition shown in FIG. 5, the valve defined by groove 78 and seal member114 being opened and positive pressure is applied through the spacebetween bore and shaft 48 to chamber 46 to dispense any materialremaining in that sample tip. The output of one shot circuit 116 alsoremoved conditioning level from AND circuit 254 via inverter 256 andthus removes the conditioning signal applied to AND circuits 260 and 264so that the shaft member 48 remains in this position while blower 216 isoperating. However, the motor control circuitry is conditioned so thaton termination of the output from one shot circuit 218, winding 214 isenergized to move shaft member 48 upward. As the flip flop 200 is set,conditioning AND circuit 272, the first transition signal on line 226 ispassed by the conditioned AND circuit 272 to clear flip flop 204 andstop motor 56 with datum reference 178 aligned with the lightsource-photocell sensor. Thus the dispenser has been reset to its datumor initial starting point from which the next aspirate sequence will beinitiated.

If for any reason, the upper travel limit 176 should be sensed, logic220 generates a signal on line 274 to initiate a dispense sequenceautomatically and discharge material from sample tip 46.

In a specific example of use of this dispenser system in a biochemicalanalysis for serum glucose, all three cuvette chambers 36 initiallycontain 4 milliliters of liquid reagent (6 percent orthotoluidiene inglacial acetic acid) when it is received by the user together with acorresponding (Glucose) data card 30. With the data card positioned incard reader 20, the card reader has an output over lines 252 to comparecircuit 212. A glucose serum standard (containing a precisely determined200 milligrams per milliliters and coordinated with the glucose datacard 30) is placed beneath the sample tip 46-1 and the control 16-1 ismoved to the aspirate position so that 100 microliters (mark 180-3) ofthe standard is placed in the sample chamber 46-1. The same amount (100microliters) of a sample of the serum to be analyzed is similarly placedin the chamber of dispenser 14-2 through operation of control 16-2. Thecuvette 24 is then positioned so that chambers 36-2 and 36-3 are alignedwith dispensing chambers 46-1 and 46-2, respectively, and then bothcontrols 16-1 and 16-2 are moved to dispense position to discharge thesamples into chambers 36-2 and 36-3. Nothing is added to chamber 36-1.After the chambers have been rescaled and the contents mixed byinversion, the cuvette assembly 24 is placed in a unit of the incubator18 and incubated at 100C for 20 minutes. When the incubation period iscomplete, the cuvette 24 is placed in the photometric recess 22, thephotometer being set in accordance with data on the associated glucosedata card 30, and a photometric analysis of the materials in the threechambers 36 is made. The output digital value displayed at display 26 isdirectly proportional to the concentration of glucose in the sampleserum in units of milligrams per 100 milliliters.

Thus, the invention provides convenient and versatile system foraccurately dispensing material. it is particularly useful in conjunctionwith the performance of analyses of blood and other body fluids. Thesystem is easily operated by untrained personnel and enables analyticalinformation to be made available, quickly, accurately and inexpensively.

While a particular embodiment of the invention has been shown anddescribed, various modifications thereof will be apparent to thoseskilled in the art, and therefore it is not intended that the inventionbe limited to the disclosed embodiment or to details thereof anddepartures may be made therefrom within the spirit and scope of theinvention as defined in the claims.

What is claimed is:

l. A dispenser apparatus comprising a housing, said housing including achamber for holding a sample and said chamber having a bore therein anda port, a movable member mounted in said bore for reciprocatingmovement, rack and pinion gearing means to move said member relative tosaid chamber from a first position to a second position to aspiratematerial into said chamber through said port and to move said memberfrom said second position toward said first position to dispensematerial from said chamber through said port, and means to increase thepressure in said chamber to supplement the dispensing action produced bythe movement of said member from said second position toward said firstposition.

2. A dispenser apparatus comprising a housing, said housing including achamber for holding a sample and said chamber having a port, a movablemember coupled to said housing, means to move said member relative tosaid chamber from a first position to a second position to aspiratematerial into said chamber through said port and to move said memberfrom said second position toward said first position to dispensematerial from said chamber through said port, and means to increase thepressure in said chamber to supplement the dispensing action produced bythe movement of said member from said second position toward said firstposition, said means to increase pressure in said chamber position toaspirate material into said chamber through said port and to move saidmember from said second position toward said first position to dispensematerial from said chamber through said port, and means to increase thepressure in said chamber to supplement the dispensing action produced bythe movement of said member from said second position toward said firstposition, said means to increase the pressure in said chamber includinga source of pressure, a passage between said source of pressure and saidchamber and valve means responsive to movement of said member forcontrolling the flow through said passage.

5. The apparatus as claimed in claim 4 wherein said valve means includesa bypass groove in said member and further including a cooperating sealmember in said housing that normally engages said member in sealingrelation so that, when said member is moved to a third position, saidbypass groove is juxtaposed with said seal member and a path ofcommunication is provided between said source of pressure and saidchamber.

6. A dispenser apparatus comprising a housing, a replaceable membersecured to the end of said housing and defining a chamber for holding asample, said replaceable member being conical in configuration andhaving a port formed at the tip of said conical member, a movable membercoupled to said housing, means to move said member relative to saidchamber from a first position to a second position to aspirate materialinto said chamber through said port and to move said member from saidsecond position toward said first position to dispense material fromsaid chamber through said port, and means to increase the pressure insaid chamber to supplement the dispensing action produced by themovement of said member from said second position toward said firstposition.

7. The apparatus as claimed in claim 6 wherein said housing has a boretherein, said movable member is mounted in said bore for reciprocatingmovement, and said means to move said member includes a reversibleelectric motor coupled to said movable member by rack and piniongearing.

8. The apparatus as claimed in claim 7 wherein said means to increasepressure in said chamber includes a blower and means to connect saidblower to said chamber.

9. The apparatus as claimed in claim 8 wherein said valve means includesa bypass groove in said member and further including a cooperatingannular seal member in said housing that normally engages said member insealing relation so that when said member is moved to a third position,said bypass groove is juxtaposed with said seal member and a path ofcommunication is provided between said blower and said chamber.

1. A dispenser apparatus comprising a housing, said housing including achamber for holding a sample and said chamber having a bore therein anda port, a movable member mounted in said bore for reciprocatingmovement, rack and pinion gearing means to move said member relative tosaid chamber from a first position to a second position to aspiratematerial into said chamber through said port and to move said memberfrom said second position toward said first position to dispensematerial from said chamber through said port, and means to increase thepressure in said chamber to supplement the dispensing action produced bythe movement of said member from said second position toward said firstposition.
 2. A dispenser apparatus comprising a housing, said housingincluding a chamber for holding a sample and said chamber having a port,a movable member coupled to said housing, means to move said memberrelative to said chamber from a first position to a second position toaspirate material into said chamber through said port and to move saidmember from said second position toward said first position to dispensematerial from said chamber through said port, and means to increase thepressure in said chamber to supplement the dispensing action produced bythe movement of said member from said second position toward said firstposition, said means to iNcrease pressure in said chamber including ablower and means to connect said blower to said chamber.
 3. Theapparatus as claimed in claim 2 wherein said member has a bypass portionand movement of said member to a third position opens said bypassportion to provide communication between said blower and said chamber.4. A dispenser apparatus comprising a housing, said housing including achamber for holding a sample and said chamber having a port, a movablemember coupled to said housing, means to move said member relative tosaid chamber from a first position to a second position to aspiratematerial into said chamber through said port and to move said memberfrom said second position toward said first position to dispensematerial from said chamber through said port, and means to increase thepressure in said chamber to supplement the dispensing action produced bythe movement of said member from said second position toward said firstposition, said means to increase the pressure in said chamber includinga source of pressure, a passage between said source of pressure and saidchamber and valve means responsive to movement of said member forcontrolling the flow through said passage.
 5. The apparatus as claimedin claim 4 wherein said valve means includes a bypass groove in saidmember and further including a cooperating seal member in said housingthat normally engages said member in sealing relation so that, when saidmember is moved to a third position, said bypass groove is juxtaposedwith said seal member and a path of communication is provided betweensaid source of pressure and said chamber.
 6. A dispenser apparatuscomprising a housing, a replaceable member secured to the end of saidhousing and defining a chamber for holding a sample, said replaceablemember being conical in configuration and having a port formed at thetip of said conical member, a movable member coupled to said housing,means to move said member relative to said chamber from a first positionto a second position to aspirate material into said chamber through saidport and to move said member from said second position toward said firstposition to dispense material from said chamber through said port, andmeans to increase the pressure in said chamber to supplement thedispensing action produced by the movement of said member from saidsecond position toward said first position.
 7. The apparatus as claimedin claim 6 wherein said housing has a bore therein, said movable memberis mounted in said bore for reciprocating movement, and said means tomove said member includes a reversible electric motor coupled to saidmovable member by rack and pinion gearing.
 8. The apparatus as claimedin claim 7 wherein said means to increase pressure in said chamberincludes a blower and means to connect said blower to said chamber. 9.The apparatus as claimed in claim 8 wherein said valve means includes abypass groove in said member and further including a cooperating annularseal member in said housing that normally engages said member in sealingrelation so that when said member is moved to a third position, saidbypass groove is juxtaposed with said seal member and a path ofcommunication is provided between said blower and said chamber.